Via Adam Kilgore of the Washington Post, Davey Johnson explains the aftermath of the double-switch:

"I told [bench coach] Randy [Knorr], ‘Tell the kid, I have one player left and I’m double switching with him,’ so he doesn’t kill himself down there,” Johnson said. “He didn’t get to him right away. [Harper] was destroying helmets in the runway. So I said, ‘Randy, will you get to him? Please get to him.’ But I really had no choice. I didn’t care if it was Babe Ruth. I had one player left and I have to have as many batters to stay in the game as possible."(Davey Johnson via Nationals Journal, 8/26/2012)